1. Field of the Invention
The present invention relates generally to a grinding wheel used for grinding the outer circumferential surface of a roll as installed on given equipment, and more particularly to such a grinding wheel which has high impact or shock resistance and which is less likely to chip or be otherwise damaged.
2. Discussion of the Prior Art
Rolling surfaces of working rolls on a rolling mill, for example, may be roughened due to rolling contact with workpieces such steel ingots, billets and slabs, or locally excessively worn at the opposite end portions which contact the lateral end portions of the workpieces. Similar wearing conditions are encountered on other types of rolls such as back-up rolls which are provided for backing up the working rolls. Therefore, the outer circumferential surfaces of such rolls need to be ground to desired smoothness. To this end, there has been proposed a so-called "on-line" grinding method, in which a roll is ground by a cylindrical grinding wheel, for example, while the roll is installed on a rolling mill stand. In this instance, the grinding is effected such that the grinding wheel is negatively rotated by a rotating movement of the roll, or positively rotated by suitable drive means such as a motor, while the working end face of the wheel is held in pressed frictionally sliding contact with the outer circumferential surface of the roll. Typical examples of such a method and grinding devices for practicing the method are disclosed in laid-open Publication Nos. 61-140312, 61-154706 and 62-127109 of unexamined Japanese Patent Applications. According to the "on-line" grinding method disclosed therein, the rolls may be ground with higher efficiency, with a result of higher operating efficiency or productivity of the rolling mill, than in the case where the rolls are ground after they are removed from the rolling mill. The grinding devices disclosed in the above Publication Nos. 61-140312 and 61-154706 are adapted such that the grinding wheel is negatively rotated by the rotation of the roll to be ground, while the grinding device disclosed in the above Publication No. 62-127109 is of the type in which the grinding wheel is positively rotated by a drive motor In a common "on-line" grinding as described above, a plurality of grinding wheels are arranged in a line parallel to the axis of rotation of the roll, such that the grinding wheels are spaced apart from each other, and the grinding is conducted while the wheels are reciprocated in the axial direction of the roll.
When the "on-line" grinding is effected while the roll is engaged in a rolling process, the grinding wheel may suffer from chipping, cracking or other damages at the radially outer peripheral edge portion of the grinding end face, due to vibrations of the roll in the process of rolling a workpiece, or due to collision of the grinding wheel with irregular stepped or raised portions or protrusions formed on the rolling surface of the roll, which arise from local wearing of the rolling surface.